Elevator Safety.

An elevator in Chicago plummeted dozens of stories before stopping https://www.bbc.com/news/world-us-canada-46274458. I thought that old man Otis had solved that problem years ago, and that once tension in the cable is released brakes automatically stick out the sides to stop the elevator. What’s the deal?

Otis solved that problem. There are other, rarer, problems that can cause elevators to fall.

E.g. the brakes can also fail.

Apparently not.

Indeed, Otis solved the problem in the 19th century with a failsafe grip system that could be understood easily and couldn’t possibly be disabled. In the past few decades, elevator companies, including Otis, have shifted to more subtle emergency braking systems, some of which rely on electronics and can be disabled for servicing. Here’s a Washington Post article describing modern systems.

And note that nobody was killed, or even injured in this incident. So you could say the fail-safe systems worked.

They fell from the 95th to the 11th floor before stopping. I’m sure that some underwear had to be changed.

Unless an elevator has a load in it will fall up not down.
1 cable breaking will not cause the elevator to fall.
The safety factor of elevators is so high that a car can be held if all but one of the cables break.

If an elevator fell from the 95th floor to the 11 floor It should not take hours for the fire department to get people out. They would not need to Cut a hole through the wall. Just use the Jaws of life and pry open the doors. And the picture that went with showed a bare cement block wall and a bare cement floor. In a high rise build.
If one cable broke and the elevator kept moving at some point the broken cable is going to start sliding off the traction wheel and fall down the shaft. A cable falling from 95+ floors is going to make a lot of noise going down the shaft and when it hits the top of the car it will be a very loud.
My SWAG something happened and the elevator motored down from the 95th floor to the 11 floor until one of the safeties tripped and shut down the elevator with a jerk.
I can not count the times I heard someone claim that the elevator they were in free fell and it did not.
My dad was in an old elevator where the cables did break. It free failed about 18 inches before the mechanical emergency breaks stopped the car.
I think the story is a made up story.

You’re assuming there was an opening for the elevator on that floor. Apparently, there wasn’t. From the Chicago Tribune, “The not-so-express elevator was stuck somewhere between the 95th floor and the lobby of Chicago’s fourth-tallest building, one of several cables holding it having broken. It was in a “blind shaft” with no openings firefighters could use to inspect it or reach the trapped — among them tourists from Mexico who had taken it from the Signature Room shortly after midnight.”

I have only been a few buildings with express elevators, so I did not think about by passed floors not having doors. But still in one of the pictures that I saw elsewhere the wall was a bare cement block wall and the floor was unfinished on the 11th floor of a completed high rise. That does not add up.

Behind a paywall. You gotta pay the WaPost to read it.

Behind a paywall. You gotta pay the ChiTrib to read it.

What’s the world coming to, with no free news anymore?

According to press reports, the fire department broke through from a parking garage, which probably explains the “unfinished floor” you perceived.

They fell 84 floors before the fail-safe systems kicked in. If they had started on the 83rd floor they would have impacted the ground. I wouldn’t call 83 floors of fail-safe systems failing to do anything ‘working’. It’s a ‘thank-fuck-it-finally-worked’ system.

Did not see that in any of the reports I read. But Garage above the 11th floor?

The elevator would have stopped by end of shaft safeties before it impacted the ground. The safeties would have shut the motor and generator down, and the elevator motor brakes would have stopped the car.

The garage starts on the 6th floor. It’s accessed by a spiral ramp next to the building.

I too doubt that the elevator ‘plummeted’.

I would say that it descended normally and then, when the cable failed (or whatever), the cabin dropped a short distance before the safeties kicked in.

Dumb question (or maybe not)…

Why can’t there be a big, cushiony object at the bottom of each shaft to absorb the impact of a free-falling elevator car?

I’m thinking of specialized barriers I see near concrete structures on highways that are designed to absorb (some of) the impact of a moving vehicle.

I’m about the last thing from an elevator expert. However, one possible answer–which holds true for a LOT of things–is that it simply is not worth the expense to install equipment to mitigate every possible scenario.

There is, at least on some elevators. Though I don’t think they are designed to safely stop an elevator free-falling from the top.

Looking at the humongous air mattresses used for saving the lives of stuntpersons, I cannot imagine what it would take to safely slow down a very heavy elevator filled with people free-falling fifty or more stories